Embedded sound
We demand ever more powerful technologies, while expecting them to be smaller, more compact and discreet. So perhaps in an age of ultra-small MP3 music players it’s no surprise to hear of ultra-thin loudspeakers, yet the dimensions of the loudspeaker developed by Warwick Audio Technologies is remarkably small. ‘The mesh material we use is less than 0.25 millimetres thick’, explains the company’s Chief Executive Officer, Steve Couchman. The size of the loudspeakers opens up new possibilities for better sound in public spaces, from travel information in train stations, to information about products in shopping centres. ‘To use the speaker effectively,’ says Couchman, ‘you need to put it into some sort of frame. So if we had some sort of back frame we could use that as a material on its own, for example it could be a hanging poster in a supermarket. As you approach it would then say something like “these oranges are the best from Spain, would you like to try them?” that sort of thing.’

Prototype
The inventors are Dr Duncan Billson and Professor Hutchins of the University of Warwick, says Couchman. “The concept came out of the University’s Ultrasonics Group. It dates back to 2002 when they made the discovery.”  Originally Billson and Hutchins conducted trials creating sound with two sheets of tin-foil and an insulating layer of baking paper. The current prototype is constructed from a number of films and a metallised back-frame. ‘That metallised back-frame,’ says Couchman, ‘can be very flexible material which means the whole of the speaker can be flexible, or it can be a very stiff material.’

Surround-sound
They have experimented with the speaker as a ceiling tile, and have even incorporated it around a 360 degrees lampshade. The construction of the speaker gives crisper, sharper sound. There’s been lots of interest in its potential, from building it into whiteboard technology, to fitting it in cars. To get the best sound in cars says Couchman, ‘the ideal place for speakers is in the headlining. Manufacturers until now have not been able to do that because of space, and because it would increase the weight and change the car’s centre of gravity. One thing you don’t do is change the centre of gravity after it has been designed.’ It is a truly surround-sound technology.